1. Field of the Invention
This invention relates generally to telephone devices. More particularly, it relates to apparatus and techniques to identify services utilizing a telephone line, allowing a field technician the ability to interrogate a telephone line to determine any/all services which may be present.
2. Background of Related Art
There has been an explosive growth in the use of telephone lines in many households, driven largely by the need for simultaneous Internet access, voice communications, networking, etc. Many households and small business are already wired with a telephone line, providing the basis for a convenient wired network.
Currently, as many as five (or more) services may co-exist on a single copper pair (i.e., telephone line). They are voice band service (POTS), ISDN service, ADSL service, HPNA (Home Phone line Network Alliance) service and VDSL service. HPNA exists within a home on an internal copper pair, the other services are delivered to the home on an external copper pair.
FIG. 6. shows a conventional distribution of spectral regions typically used for various services, e.g., voice services, xDSL services such as ADSL and g.Lite or G.922.2, and of a home network such as HPNA. As shown in FIG. 6, a single telephone line is shared such that the various services co-exist as a type of FDM (Frequency Division Multiplex) system. In this arrangement, Plain Old Telephone Service (POTS) exists in the 0-4 kHz region, an exemplary xDSL service may be present from 25 kHz to approximately 2.2 MHz (depending on the definition of xe2x80x9cxxe2x80x9d), and the HPNA spectrum occupies 5.5-9.5 MHz for HPNA V1.x technology or 4.25-9.75 MHz for the emerging V2.x technology.
Correct operation of various wire line services depends on the type of equipment installed in the customer premises. FIG. 7 shows the conventional utilization of various services by various equipment connected to a telephone line 701 at a customer premises. For instance, as shown in FIG. 7, a customer premises may include equipment such as a telephone 710, an ISDN interface 712, an ADSL interface 714, a home network such as HPNA 716, and a VDSL interface 718, all connected to a common telephone line 701 from a central office 702.
Correct operation of this xe2x80x9cFDMxe2x80x9d system including various services and equipment requires installation procedures that preserve the broad band nature of the copper pair telephone line 701. Moreover, interference with other wire pairs may also present a problem to the telephone technician. Technicians must install the various equipment 710-718 properly to prevent undesirable interference.
The same telephone technicians that initially installed the equipment 710-718 installed in the customer""s premises may remember which services are present and/or which equipment was installed, or the particular services and/or equipment may be presented on a work order or other information source. However, over time, the various services may be discontinued and/or some of the equipment 710-718 may be disconnected. Moreover, changes may take place to the telephone line changing the current nature of the telephone line 701 at any moment. Furthermore, as more and more telephone service providers enter the marketplace and competition heats up, detailed information regarding the particular services provided to a customer""s premises may not be known or available to a future telephone service technician.
There is a need for a workable identification apparatus and method to allow telephone line technicians the ability to interrogate a telephone line at a customer""s premises to determine how many services are present, and/or to determine the identity of the various services present.
In accordance with the principles of the present invention, a line identification device comprises a first tuned circuit having a particular resonance frequency, and a connection to connect the first tuned circuit across a tip and ring of the line. The first tuned circuit insubstantially changes an impedance of the line at frequencies of normal operation of the line.
A method of providing an identification of existing functions of a telephone line in accordance with another aspect of the present invention comprises placing a first tuned circuit across a tip and ring of the telephone line to represent an aspect of a first type of customer equipment connected to the telephone line. The first tuned circuit insubstantially changes an impedance of the telephone line at frequencies of normal operation of the telephone line.
A method of field determining a presence of a particular service to a telephone line in accordance with yet another aspect of the present invention comprises temporarily applying a test signal to the telephone line. The test signal comprises a signal at a predetermined frequency. A current of the test signal is measured at the predetermined frequency. An increase of the measured current above a current at other frequencies on the telephone line indicates a presence of the particular type of customer equipment.